Of same place



(No Model.)

W. W. DEAN. TELEPHONE EXGHANGE SYSTEM.

Patented Sept. 14,1897.

' NITE STATES \VILLIAM \V. DEAN, OF ST. LOUIS, MISSOURI, ASSIGNOR TO THEBELL TELEPHONE COMPANY OF MISSOURI, OF SAME PLACE.

TELEPHONE-EXCHANGE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 590,136, datedSeptember 14, 18197.

Application filed November 8, 1896.

To all whom it may concern:

Be it known that 1, WILLIAM W. DEAN, a citizen of the United States,residing at St. Louis, in the State of Missouri, have invented a certainnew and useful Improvement in 'lelephone-Exchange Systems, (Case No.17,) of which the following is a full, clear, con-' cise, and exactdescription, reference being had to the accompanying drawing, forming apart of this specification.

In my Patent No. armor, of August 13, 1895, I have shown meansconsisting of two electromagnetic devices and circuits associatedtherewith, whereby signaling-current is directed over the line'of thesubscriber called for by the act of the operator in inserting a pluginto the called-subscribers spring-jack at the central office, apparatusat thecalledsubscribers station being adapted to remove thesignaling-current from the line when a call has been respondedto. In myapplication for United States Letters Patent for improvement intelephone systems, Serial No. 607,126, filed September 28, 1896, I haveshown and described a telephone-exchange system in which the line-wireswere led from subscribers stations to suitable switches at the centraloffi-ce, plugs and cords being provided to connect subscribers forconversation, an electromagnetic device being associated with each setof plugs and cords adapted to include the calling-generator in circuitwith the subscribers calling apparatus, and a second electromagneticdevice within the control of the called subscriber adapted to remove thecalling-generator from line and to prevent the reinclusion of saidgenerator with the subscribers calling apparatus while con nectionexists between the subscribers.

In the system disclosed in the aforesaid application two electromagneticdevices were employed to accomplish the desired result- Viz., that ofpreventing the resignaling of a subscriber after the first signal hasbeen responded to during an established'connection, this resignalingbeing a defect inherent in the system disclosed in my aforesaid patent.

My invention herein contemplates the use of a single electromagnetassociated with each pair of plugs in combination with circuitsassociated therewith and controlled thereby,

serial No. 610,901. (No model.)

whereby the calling-generator may be included in circuit with thecalledsubscribers signal apparatus, and whereby the generator may beremoved from line by means of the called-subscribers apparatus when thesignal is responded to. In accordance with my invention these circuitsare further controlled by the apparatus at the called-subscribersstation in amanner to prevent said electromagnet from reincluding thecalling-generator in circuit with the signal apparatus after the signalhas been responded to.

My invention will be more readily understood by reference to theaccompanying drawing, which illustrates a telephone-exchange systemequipped with the apparatus of my invention.

Two subscribers stations A Bare shown in the drawing. The apparatus ateach station comprises a telephone switch-hook a, a signal-receivingbell a of, say, five thousand ohms resistance, a transmitter atelephonereceiver a and magneto-generator of. The telephone-hook atsubscribers station A is connected with the line-spring b of thespringjack 1) at the central office by the limb 1 of the telephone-line.The receiver a is connected with the line-spring b of said spring jackby a limb 2 of the telephone-line. When the telephone is hung on theswitch, as shown at station A, limbs 1 and 2 of the telephoneline aredisconnected through the receiver. The signal-bell a andmagneto-generator a are included in a bridge between the limbs 1 and 2of the telephone-line. The subscriber B is similarly connected with thecentral office, limb 3 of the telephone-line extending from theswitch-hook to the line-spring c of the spring jack 0, while thetelephone-receiver is connected with the line-spring c of saidspring-jack by a limb 4E of the telephoneline. The signal-bell a andmagneto-generator aare likewise included in a bridge between the limbsof the telephone-line.

, Back contacts Z2 1) are engaged by the linesprings 12 b? when saidline-springs are not en gaged by a plug. These back contacts areconnected by a conductor 5, in which is included the helix of theline-drop or annunciator d. Back contacts 0 c are likewise normallyengaged with the line-springs c 0 ICO These back contacts are connected.by a conductor 6, which includes the helix of a lineannunciator 8.Metallic thimbles U c are provided in connection with each spring-jack,which are adapted to guide plugs g and h as they are being insertedwithin the springjacks into contact with the line-springs.

The line-signals cl and c are adapted to be operated by themagneto-generators a" a in the well-known manner, these signals beingadapted to be included in circuit with the magneto-generators throughthe medium of the telephone-lines and the line-springs engaging the backcontacts.

The plug g is the connecting'plug, while the plug h is theanswering-plug. Plug g is provided with three contact-terminals g g 9adapted to engage the line-springs b b and the thimble 11 respectively.Plug h is provided with two contact-terminals 72, 7L2, which are adaptedto engage the line-springs 0 0 respectively. The heel portion lbs of theanswering-plug is preferably of insulating material. Terminals g h ofthe plugs are connected by the conductor 7. The terminals g h areadapted to be connected by a conductor 8, which is adapted to include acontact portion i or a contact portion 7a, according to the condition ofuse of the apparatus at the central office, as will be set forthhereinafter.

A telephone-key Z is provided for the purpose of bridging thetelcphoneoperatofis tele-,

phone set Z between the conductors 7 and 8.

At the central office I have shown an electromagnet comprising a core972, about which is placed two helices m m and an armature 'lt, pivotedat a, which is adapted to be attracted by said core when energized. Thisarmature carries plates 2', k, and 0, which carrysprin gs 1'', 7c, 0,respectively,which are adapted to in akc contact with adjustablecontact-anvils p, q, and r, respectively,while the armature carries acoi'ltact spring n adapted to make contact with adjustable contact-anvils. The electromagnet is normallydeenergized, whereby the armature andparts mounted thereon are caused to assume the normal position shown bythe spring a a stop 0 being provided which engages the plate 0 to limitthe upward m0vement of the armature and contact parts carried thereby.When the parts are in this position, the conductor 8 is broken at q andcontact-spring n is removed from anvil 5, while the anvilsp and r are incontact, respectively, with the springs t" and o.

The calling-generator t, which is preferably constructed to generatealternating currents, is included in circuit with a conductor 9,whicl1includes the helix m and which terminates in the anvils p and r. Thehelix m is included in the conductor 10, which has one of its terminalsin the anvil s, the other terminal s of said conductor being connectedwith the thimbles b c of the spring-jacks by conductors 11 and 22,respectively. Conductor 10 also includes in its circuit a battery u.

lVhen the armature n is attracted, as will be hereinafter set forth,circuit through the battery :1 and the helix m is closed by theengagement of spring 11 electrically connected with armature wandcontact-anvil s. Armature n is connected with heel-piece g by aconductor 13, this heel-piece serving to close the circuit through thebattery it when it is in contact with metallic thimble b Instead ofemploying metallic thimbles b c and the metallic heels g of theconnectingplugs for closing circuit through the battery it and helix m,I may employ the device shown in dotted lines, which consist-s of alever r, pivoted at v and carrying at its free end a socket r adapted toreceive the connectingplug. A contact-anvil o is connected by aconductor 14 with the terminal 8 of conductor 10, while the lever isconnected bya conductor 15 with the spring 72 \Vhen the connecting-plugis removed from its socket, the lever c is elevated by the spring 1%,whereby con- 1 tact is made between said lever and the anvil '0 Theclearing-out indicator to, of high retardation, is included in a bridgebetween the conductors 7 and 8, which is adapted to be operated by themagneto-generator at either subscrihers station when conversationbetween connected subscribers has been finished.

The helix m is in a bridge between the cord-strands, this helix thusoffering no impedence to the voice-currents. I

Having thus specifically set forth the apparatus of my invention, I willnow particularl y describe the manner by which signalingcurrent istransmitted over the telephonelines to the call-bells at the subscribersstations.

Subscriber B, desiring communication with subscriber A, operates hismagneto-generator a, thereby actuating his line-signal e. The operator,in response to the signal, inserts the answering-plug it into thecalling-subscribers spring-jack and depresses her listening-key Z toinclude her telephone set in circuit with the calling-subseribefstelephone set. The operator having ascertained the connection desiredinserts a connecting-plug g into the spring-jack Z) of the calledsubscriber The operator by this act includes the generator t in circuitwith the called-subscribers signal apparatus, which circuit may betraced from anvil 19 through said generator, conductor 9, helix mincluded in said conductor, anvil 0, spring 0, and contact-plate 0,thence by conductor 16 and conductor 7 to the contact-terminal g uponplug 9, thence through linespring limb 2 of the telephone-line, highresistance signal-bell a, limb 1 of the telephone-line, line-spring I),contact 9', conductor 8, contact-plate t', and contact spring 2" back tocontact-anvil p. The bell a, being of high resistance, serves to reducethe current emanating from generator 15 sufficiently to prevent thenecessary energization of the core or required to attract the armaturen.

The bell at the called-subscribefis station will. respond. to thecurrent from generator 11 until the called subscriber removes histelephonereceiver from its hook, whereby the'high resistance included inthe bell a will be shunted by the path of low resistance through thetelephone-receiver, this path of low resistance serving to increase thecurrent from generator t, whereby the core or is energized sutlicientlyto attract the armature n. The local circuit, including the battery it,which was previously opened, is now closed by the contact between anvils and spring 11 whereby the armature is maintained in its attractedposition during the time that a connection exists between the twosubscribers.

The connection of the generator 25 with the calling apparatus at thecalledsubscribers station is broken at p and T when the armature isattracted, and it is obvious cannot be reincluded in circuit with thecalled -subscribers bell while the subscribers are con-,

nected.

The sprin gs 0, 2', 7t, and n are so mounted and constructed that anvilsq and s are brought into contact with the springs and M, respectively,before anvils p and r are removed from contact with springs 71 and 0,respectively, whereby the circuit through battery it and helix m may beclosed before circuit through helix m is opened.

The electromagnet and the armature n, acting in opposition thereto withthe parts carried by said armature, constitute the means which Ipreferably employ for associating and disassociating the generator withthe telephonic conductors. Other instrumentalities or devices acting inopposition to the electromagnet may be employed without de parting frommy. invention.

Having now fully described my invention, I claim as new and desire tosecure by Letters Patent 1. Two telephone-1ines, each provided with aswitch at the subscribers station thereon, and at the central officeswitching devices for uniting said lines in combination with asignaling-generator adapted to be closed to the called-subscribens linewhen the lines are united, an electromagnetic circuit-changing device,provided with two windings or helices, one winding being connected withthe generator-circuit and the other being connected in a local circuitcontaining two openings and a source of current, one of said openingsbeing closed when the lines are connected together, the switch of thecalled subscriber when operated being adapted to reduce the resistanceof the circuit containing the signaling-generator, to increase thecurrent traversing the said coil connected with said generator, tooperate the said electromagnetic circuit-changin g device, to close theother opening of the local circuit, and immediately thereafter to openthe connection between the generator and the coil or winding of theelectromagnetic circuit-changing de vice connected therewith.

2. Two telephone-lines, each provided with a switch at the subscribersstat-ion thereon, and at the central office switching devices foruniting said lines in combination with. a signaling-generator adapted tobe closed to the called-subscribers line when the lines are united, anelectromagnetic circuit-changing device provided with two windings orhelices, one winding being connected with the generator-circuit and theother being connected in a local circuit containing two openings and asource'of current, one of said openings being closed when the lines areconnected together, the switch of. the called subscriber when operatedbeing adapted to reduce the resistance of the circuit containing thesignalirig-generator, to increase the current traversing the said coilconnected with said generator, to operate the said electromagn eticcircuit-chan gin g device, to close the other opening of the localcircuit, to open the connection between the generator and the coil orwinding of the electromagnetic circuitchanging device connectedtherewith.

In a telephone-exchange system, a local circuit at the central office incombination with connecting apparatus for uniting lines together, and anelectromagnetic circuitchanging device connected in said local circuit,said local circuit when not in active use containing two openings, oneof which is adapted to be closed by said connecting apparatus when inuse, and 'means for closing the other opening in said local circuit todirect current through said local circuit and thereby lock theelectromagnetic circuitchanging device in position during the time thesaid connecting apparatus remains in service.

4. In a telephone system, the combination with telephone-lines united atthe central station, of an automatic telephone-switch and a signaldevice at each subscribers station, a signaling-generator, means forincluding the generator in circuit with the signal device at thecalled-subscribers station,an electromagnetic circuit-changing deviceprovided with a single electromagnet,the called-subscribers switch beingadapted to change the circuit i11- cluding the circuitchanging device tooperate the same to remove the generator from line nalin g-generator,means forincluding the genthe called-subscribcfis station, thecalled-subscribcrs switch being adapted to change the circuit conditionof the circuit-changing device to operate the same to remove thegenerator from line upon the removal of the telephone-receiver,substantially as described.

6. In a telephone system, the combination with the united circuit of twotelephone-lines, each provided with a signal device at the subscribersstations thereof, of asignaling-generator, means for including thegenerator in circuit with the signal device at the calledsubscribersstation, an electromagnetic circuit changing device, switches at thesubscribers stations, each switch being adapted when its station is thecalled station to change the electrical condition of the circuitcontaining the circuit-changin g device to operate the same to removethe generator from line, a local circuit which is adapted to be closedby said circuit-changin g device through the electromagnet thereof whensaid device is thus actuated, and switching apparatus at the centralottice for uniting and disconnecting the telephone-lines, said switchingapparatus being adapted to open said local circuit when manipulated oroperated to break connection between two telephone-lines, substantiallyas described.

7. In a telephone system, the combination with the united circuit of twotelephone-lines, each provided with a signal device at. thesubscribersstations thereof, of a signaling-generator, means forincluding the generator in circuit with the signal device at thecalledsubscribcrs station, an electromagnetic circuit-changing device,switches at the subscribers stations, each switch being adapted when itsstation is the called station to change the electrical condition of thecircuit containin g the circuit-changing device to operate the same toremove the generator from line, a circuit which is adapted to be closedby said circuit-chan gin gdevice through the electromagnet thereof whensaid device is thus actuated, and switching apparatus at the centraloffice for uniting and disconnecting the telephone-lines, said switchingapparatus being adapted to open said circuit including thecircuit-changing device when manipulated or operated to break connectionbetween two telephone-lines, substantially as described.

In witness whereof I hereunto subscribe my name this 29th day ofOctober, A. D. 1896.

, WILLIAM XV. DEAN.

\Vitnesses:

TI-IOS. E. FLAHERTY, W. E. I-IARKNEss.

